Based on most discussions online and at conferences, there seem to be 2 kinds of projects that use Hibernate for their persistence layer: So, what’s the difference between these projects? Are the projects in the 2nd group more complex or have higher performance requirements? No, based on my consulting projects, that’s not the case. On…
Databases support various data types to store date and time information. The most commonly used ones are: You can map all of them with JPA and Hibernate. But you need to decide to which Java type you want to map your database column. The Java language supports a bunch of classes to represent date and…
There are various reasons to implement your own primary key representation. Your primary key may consist of multiple attributes. Or you’re following domain-driven design principles and want to use a custom type to add semantic meaning to it. Implementing a record and mapping it as an IdClass seems evident in these situations. A record is efficient, easy to implement, immutable…
The Date and Time API, introduced in Java 8, finally replaced the old java.util.Date. It’s much easier to use and finally offers separate classes representing date, date with time, and only time information. That not only improves your business code but also makes it easier to use them as entity attributes. At least if you’re…
Choosing the right FetchType is one of the most important decisions when defining your entity mapping. It specifies when your JPA implementation, e.g., Hibernate, fetches associated entities from the database. You can choose between EAGER and LAZY loading. The first one fetches an association immediately, and the other only when you use it. I explain…